Laymen often confuse and confute "personality" with "character" and "temperament".
Personality disorders are dysfunctions of our whole identity, tears in the fabric of who we are. They are all-pervasive because our personality is ubiquitous and permeates each and every one of our mental cells. I just published the first article in this topic titled "What is Personality?". Read it to understand the subtle differences between "personality", "character", and "temperament".
In the background lurks the question: what constitutes normal behavior? Who is normal? (From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 2 DVDs with 12 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)